The invention relates to a variable valve control arrangement for an internal combustion engine having a valve operating mechanism including two camshafts whose angular position relative to each other is controllable by a four-gear coupler drive which is disposed in the drive connection between the two camshafts and which is controllable by a control arrangement including a control motor and a control gear arranged co-axially with one of the camshafts and operable by the control motor by way of a drive pinion.
Variable valve controls of this type are known for example from DE 42 44 550 A1 and from DE 195 21 004. They are used particularly for a throttle-free control of gasoline engines by changing the opening rates and opening times of the intake valves. Basically, such valve controls include two camshafts which rotate in opposite directions and which actuate, by way of their cams, together the rocker arm for a spring-loaded intake valve. One of the camshafts takes on the valve opening function while the other has the valve closing function so that, with a relative rotation between the two camshafts, the valve lift and the valve opening period are controllable over a wide range.
The relative rotation between the two camshafts is obtained by way of a four-gear coupler drive whose input gear is connected to a first camshaft which is driven by the crankshaft and whose output gear is connected to the second camshaft which is driven by the coupler drive so as to be rotatable relative to the first camshaft. The input gear and the output gear are each in engagement with intermediate gears and the intermediate gears are in engagement with each other. The input gear, the output gear and the intermediate gears are interconnected by coupler members such that the intermediate gears roll off the input and output gears when the coupler members are pivoted. In this way, by pivoting of the coupler drive by means of a control member, which is pivotable about the axis of the input or the output gear and which is connected to the respective coupler member, the two camshafts can be rotated relative to each other. The control member is operated by a control motor and the control arrangement formed by the control member and the control motor provides for a sensitive adjustment control of the coupler drive. As a result, the load can be controlled in a correspondingly sensitive manner.
Variable valve controls of this type are relatively complex and therefore their basic setting is not easily adjustable since, in addition to the camshaft drive, a control arrangement with a separate drive including a control motor is required.
It is the object of the present invention to provide such a variable valve control which is easy to install and to adjust and which furthermore takes up only a relatively small space.